async function async1 () {
    console.log('async1 start'); //
    await new Promise(resolve => {
        console.log('promise1') //
    })
    console.log('async1 success'); // 永远阻塞了
    return 'async1 end'
}
console.log('srcipt start')   //
async1().then(res => console.log(res)) // 拿不到return值了 也阻塞了
console.log('srcipt end') //


/*
? srcipt start
? async1 start
? promise1
? srcipt end

 */
